Below in simple outline form is one method of sharing the gospel that I have found to be simple and easy to understand.

1. God's demand: Perfection

But there shall by no means enter it [the New Heavenly Jerusalem] anything that defiles, or causes an abomination or a lie, but only those who are written in the Lamb’s Book of Life.

— Revelation 21:27

See also: Psalm 5:4; Habakkuk 1:13

2. Man's condition: We are sinful, not perfect

But we are all like an unclean thing, and all our righteousnesses [the best we can do] are like filthy rags; we all fade as a leaf, and our iniquities, like the wind, have taken us away.

— Isaiah 64:6

See also: Romans 3:10, 3:22–23; James 2:10; Ecclesiastes 7:20

3. God's provision: The Lord Jesus Christ

All we like sheep have gone astray; we have turned every one to his own way; and the Lord has laid on Him [Jesus] the iniquity of us all.

— Isaiah 53:6

For He [God] made Him [Jesus] who knew no sin to be sin for us, that we might become the righteousness of God in Him.

— 2 Corinthians 5:21

And He Himself [Jesus] is the propitiation [satisfaction] for our sins, and not for ours only but also for the whole world.

— 1 John 2:2

See also: Romans 6:23; 1 Peter 3:18

4. Man's response: Believe in Christ

But to him who does not work but believes on Him who justifies the ungodly, his faith is accounted for righteousness.

— Romans 4:5

For by grace you have been saved through faith, and that [being saved] not of yourselves; it [being saved] is the gift of God, not of works, lest anyone should boast.

— Ephesians 2:8–9

See also: John 3:18, 3:36, 20:31; Acts 13:38–39

Note: to "believe" in or on Christ means to trust Him as you might "believe in" your best friend or your spouse. It is not merely believing certain truths about Him; it means you are depending upon Him to do what He has promised to do, to give eternal life to those who do believe in Him.

5. God's guarantee: Eternal life

And this is the testimony: that God has given us eternal life, and this life is in His Son. He who has the Son has life; he who does not have the Son of God does not have life. These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life.

— 1 John 5:11–13

See also: John 5:24, 6:47, 10:28–29

If you commit these five major points to memory, along with a few corresponding verses with each point, you will always be able to explain the way of salvation to others.

Keeping the main thing the main thing

Virtually every time you witness, the real issue will be: Are we saved by grace or by works? Some think that although works cannot save by themselves, they certainly can't hurt! When it comes to salvation, however, works cannot save. By inserting good works into the salvation formula, the true biblical gospel is corrupted so that it becomes a false gospel that does not save. Consider just three key passages:

For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast.

— Ephesians 2:8–9

But to him who does not work but believes on Him who justifies [declares righteous] the ungodly, his faith is accounted for righteousness. 

— Romans 4:5

And if by grace, then it is no longer of works; otherwise grace is no longer grace. But if it is of works, it is no longer grace; otherwise work is no longer work.

— Romans 11:6

Never forget: Salvation is by grace alone, through faith alone, in Christ alone. It is never by works, nor can one achieve it by a combination of grace and works. This is the heart of the true gospel. You will not be effective in winning others if you pollute the gospel of grace by the addition of man's good deeds. Good works are expected by God from those who are His children after they are in His family by faith in Christ.

For we [believers] are His workmanship, created in Christ Jesus for [not by] good works, which God has prepared beforehand that we should walk in them.

— Ephesians 2:10

God always calls for good works after one has salvation, never as a means of achieving it.

Give the message clearly

By clearly I mean using Bible words and phrases with Bible definitions — refusing to add to God's Word things that simply are not there.

The prophet who has a dream, let him tell a dream; and he who has My word, let him speak My word faithfully. What is the chaff to the wheat, says the Lord. Is not My word like a fire? says the Lord, and like a hammer that breaks the rock in pieces?

— Jeremiah 23:28–29

See also: Isaiah 8:19–20; 2 Corinthians 3:12

Be simple

By simple I mean that as you express the clear gospel of God's grace you do it in words that anyone can understand. You may be biblically clear in your doctrine, yet not be simple; and you may be simple (easily understood), yet fail to be Scripturally clear.

For if the trumpet makes an uncertain sound, who will prepare himself for battle? So likewise you, unless you utter by the tongue words easy to understand, how will it be known what is spoken? For you will be speaking into the air.

— 1 Corinthians 14:8–9

See also: 1 Corinthians 2:1–5; 2 Corinthians 11:3

Be loving, yet give the gospel with boldness

Speaking the truth in love, [you] may grow up in all things into Him who is the Head — Christ.

— Ephesians 4:15

For I am not ashamed of the gospel of Christ, for it is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek.

Be faithful (consistent) in sharing Christ

Know the gospel thoroughly

But sanctify the Lord God in your hearts, and always be ready to give a defense to everyone who asks you a reason for the hope that is in you, with meekness and fear.

— 1 Peter 3:15

See also: 1 Corinthians 15:1–4; 2 Timothy 2:15, 2:23–26

Make sure your life enhances the gospel

Only let your conduct be worthy of the gospel of Christ, so that whether I come and see you or am absent, I may hear of your affairs, that you stand fast in one spirit, with one mind striving together for the faith of the gospel.